Here’s why: After years of dominating the enterprise, a new wave “bring your own device” mentality has opened the door for the iPhone and Android to sweep market share right out from under BlackBerry.

RIM used to depend on lucrative deals with corporations and government agencies for the bulk of its business—in early 2007, ahead of Apple iPhone launch, corporate clients made up 71% of its subscriber base, according to an earlier report in The WSJ. But that percentage has shrunk to as little as 20% to 25%, according to analysts cited in that report.

Samsung has a couple advantages, the largest of which being that its most recent smartphone — the Galaxy S III — was considered by many to be a legitimate contender with the iPhone as one of the top consumer-oriented phones.

And being a top consumer-oriented phone has its advantages, especially when employees start bringing those phones to work and demanding to use them in lieu of corporate-issued phones, which has traditionally been BlackBerry’s strongest position.

The release date of the new BlackBerry 10 devices in the U.S. also still remains unclear. Several carriers have said they plan to introduce the Z10 model but not set a firm U.S. release date– so it’s possible the S IV will beat the new BlackBerry to the U.S. market.

Samsung also unleashed a marketing blitz to promote its devices as “safe” for work. All you have to do is look at the commercials it’s aired in recent days, which pretty openly trash BlackBerry:

And now it has Samsung coming straight for it. Not an enviable position, to be sure, given that Samsung has given Apple — one of the largest and most competent technology companies in the world — a serious run for its money.

We reached out to Research In Motion for comment, but haven’t heard back yet.